1. Field of the Invention
The present invention relates to fluid exchanging apparatus and, more particularly, to a hand held control device for performing a simultaneous exchange of transmission fluid in an automatic transmission.
2. Description of the Prior Art
Automatic transmissions require transmission fluid because such fluid is employed in part as a driving means within the transmission and is additionally employed to lubricate the internal components within such transmissions. Over time such fluid becomes less viscous and thus less efficient in lubricating such components. It is therefore desirable to periodically perform an exchange of fluid to maintain the viscosity of such fluid within the transmission and to maintain the cleanliness of the transmission and thereby increase the useful life of the transmission. A complete exchange of fluid is preferred so that the used fluid as well as undesirable foreign matter contained therein is completely removed and is replaced with new, more viscous fluid.
There has been a long standing need for a device which may efficiently perform a simultaneous, substantially complete exchange of transmission fluid in an automatic transmission while at the same time posing minimum risk to the transmission. The conventional method, still widely practiced today, is to replace the fluid housed in the pan of the transmission. The pan typically holds from 1 to 5 quarts of the total 7 to 15 quart capacity of the transmission. Thus emptying the pan and then adding that amount of new fluid only serves to dilute the used fluid with some 15-25% of new fluid. Hence this conventional service is inefficient since it only serves to mix new fluid with a large quantity of used fluid. Furthermore, this service requires the removal of the transmission fluid pan from the transmission for emptying of the fluid therefrom and replacement of the pan on the transmission housing. This can prove to be a messy and time consuming process. Furthermore, the pan is often not replaced squarely over the pan seal or, on occasion, will trap small foreign obstacles in the seal area resulting in leakage.
More recently, there have been efforts to make a complete exchange of all the fluid in an automobile's transmission by disconnecting a fluid tube and draining the fluid into a waste oil dump while manually pouring new fluid into the transmission dipstick tube. This procedure has proven to be inefficient, inadequate and so time consuming that it has failed to gain broad acceptance.
Another method proposed involves disconnecting a transmission fluid cooler line to allow one disconnected end to drain freely, while the other end is connected to a relatively large pressurized bulk storage tank to inject unused fluid into the cooler line to refill the transmission. One major disadvantage associated with this method is that, in many instances, the rate at which fluid is withdrawn from the transmission is not matched by the rate of refill. As such, there is a risk that the fluid level in the transmission will drop dangerously low resulting in possible damage to the transmission pump, fluid seals, rear bearings or other internal components of the transmission. This difficulty is compounded by the fact that the flow resistance through the transmission varies with the different models of transmissions.
Another device proposed in attempt to provide for an efficient fluid exchange includes a drain hose wound on a retractable reel and connected on its free end to a drain funnel for placement beneath the vehicle oil drain pan opening for withdrawal of oil by gravity into such funnel. Such a device is shown in U.S. Pat. No. 3,140,756 to Dinkelkamp. A suction pump connected to the drain hose serves to flow such withdrawn oil to a remote waste oil tank. This device contemplates that the operator will completely drain the used oil from the engine, replace the drain plug, and manually refill the engine with unused fluid. This apparatus has not gained acceptance as a transmission fluid changer in that it fails to provide for simultaneous exchange of fluid and requires that the operator manually refill the crankcase.
Yet another device proposed in an attempt to facilitate fluid removal and replacement in an automobile fluid system includes a switching control device permanently mounted to an engine oil system, such a device being described in U.S. Pat. No. 5,056,621 to Trevino. This device includes a pump to be mounted to the engine block and a pair of input suction conduits for connection to, respectively, an oil drain port and to a source of unused oil. The device includes a switch which allows for the selection of the conduit through which fluid may flow and a pump to draw fluid through the selected conduit. An output conduit is also provided with a free end for releasable connection to a waste oil tank when the switch is in the position to flow fluid from the oil drain port, and is releasably connected to an oil filler tube when the switch is placed in the position to allow fluid to flow from the source of unused fluid. Thus devices of this type have not gained acceptance for changing transmission fluid in that they do not provide for the simultaneous exchange of fluid, are burdensome to use and time consuming because, in order to switch such a device between withdrawing and replacing fluid, the operator must manually remove the output conduit from the waste oil tank and connect such conduit to the vehicle's oil filler tube.
Other work in this field has led to the proposal of a transmission fluid changer including air pressurized tanks for supply and extraction of transmission fluid via the transmission cooler lines. A device of this type is shown in U.S. Pat. No. 5,318,080 to Viken. Such devices are rather cumbersome, require connection with a pressure hose which acts as an umbilical cord thus committing such cord on a dedicated basis and resulting in the inconvenience of the device being tethered to such cord and restricting manipulation thereof. Such devices have not gained acceptance in the marketplace.
Further efforts have led to a portable device which may perform a simultaneous, substantially complete exchange of transmission fluid. Such a device is shown in U.S. Pat. No. 5,370,160 to Parker who has granted the rights therein to the assignee of the rights in the present invention. Such a device may be utilized to adjust flow rates of the fluids being withdrawn from and introduced to the transmission. This device, while having gained acceptance in the field, suffers the shortcoming that it is bulky, occupies a substantial amount of floor space during use and is somewhat expensive to manufacture.
As such, it may be appreciated that there continues to be a need for an automatic transmission fluid exchanging device which is so compact it could be held in a user's hand but yet being operative to efficiently replace substantially all the used fluid in an automatic transmission. The instant invention addresses such needs.